Field of the Invention
The present invention relates to an in-cell touch type touch display device, and more particularly, to a touch integrated circuit (IC), and a touch display device with improved touch operation and a method of driving the same.
Discussion of the Related Art
Instead of using conventional input devices such as a mouse or a keyboard, a touch panel, which enables a user to directly input information through a screen with a finger or a pen, is being applied to display devices. Since all users can easily manipulate the touch panel, the application of the touch panel is being expanded.
Touch panels are categorized into a resistive type, a capacitance type, an infrared type, etc. depending on a touch sensing method. Recently, since the capacitance type provides convenience in a manufacturing process and is good in touch sensitivity, the capacitance type is attracting much attention. Capacitive touch panels are categorized into a mutual capacitance type and a self-capacitance type.
Recently, liquid crystal display (LCD) devices to which a touch screen is applied have been developed in an in-cell touch type where a capacitive touch sensor is built into a liquid crystal panel, for slimming the LCD devices. In the following description, a touch panel denotes that the touch sensor is built into the liquid crystal panel.
FIG. 1 is a diagram schematically illustrating a related art touch display device. FIG. 2 schematically illustrates the related art touch display device and is a diagram illustrating a rear surface of the touch display device.
Referring to FIGS. 1 and 2, the related art touch display device 1 includes a touch panel 10 and a driving circuit unit. The driving circuit unit includes a source/touch driver 30, a gate driver 40, a touch IC 50, and a timing controller.
The source/touch driver 30 includes a plurality of source/touch driving ICs 35. A half of the plurality of source/touch driving ICs 35 are disposed on an upper end of the touch panel 10, and the other half are disposed on a lower end of the touch panel 10. A plurality of touch sensors 20 are disposed in the touch panel 10, and each of the touch sensors 20 is connected to a corresponding source/touch driving IC 35 through a touch line 22.
The gate driver 40 includes a plurality of gate driving ICs 45, and the plurality of gate driving ICs 45 are disposed on both side surfaces of the touch panel 10.
One touch sensor 20 may be disposed to correspond to a plurality of pixels. For example, each of the touch sensors 20 may be disposed in an area which corresponds to forty pixels in a horizontal direction and twelve pixels in a vertical direction. In this case, each of the touch sensors 20 is configured by a common electrode which is disposed for displaying an image. That is, the plurality of touch sensors 20 are configured by patterning the common electrode.
One frame period is divided into a display period and a touch period, and a display operation and a touch sensing operation are time-divisionally performed. In the display period, a data voltage is supplied to a pixel electrode, and a common voltage (Vcom) is supplied to the plurality of touch sensors 20, thereby displaying an image. In the touch period, the source/touch driver 30 supplies a touch driving signal to each of the touch sensors 20, and the touch IC 50 receives a capacitance charged into each of the touch sensors 20 and senses a variation of the capacitance of each of the touch sensors 20 to determine whether there is a touch and detect a touch position.
In large-screen touch display devices (e.g., 86 inches or more) that display an image at a resolution of 4K ultra high definition (UHD) or more, the number of the touch sensors 20 increases in proportion to a screen size, and for this reason, the number of the touch lines 22 increases. For this reason, the number of the source/touch driving ICs 35 increases.
Lengths of the touch lines 22, which connect the touch sensors 20 to the source/touch driver 30, change depending on positions at which the touch sensors 20 are disposed in the touch panel 10. Therefore, touch sensors (for example, touch sensors disposed over and under the touch panel 10) disposed close to the source/touch driver 30 among the plurality of touch sensors 20 decrease the signal delay of each of the touch lines 22. On the other hand, touch sensors (for example, touch sensors disposed in a center area of the touch panel 10) disposed far apart from the source/touch driver 30 among the plurality of touch sensors 20 increase the signal delay of each of the touch lines 22.
In small-size touch display devices, since a signal delay deviation is small, the touch IC 50 may perform a touch operation as soon as the touch IC 50 receives a touch report of each of the plurality of source/touch driving ICs 35.
On the other hand, in large-size touch display devices, since the number of the source/touch driving ICs 35 increases, a signal delay deviation between the touch IC 50 and the plurality of source/touch driving ICs 35 increases. For this reason, a deviation occurs in delay of a touch report of each of the plurality of source/touch driving ICs 35, and consequently, the touch IC 50 may not normally perform touch operation.
FIG. 3 is a diagram schematically illustrating a video wall device.
Referring to FIG. 3, a video wall device 60 that realizes a large-screen display by using a plurality of touch display devices DP1 to DP4 arranged in a tile form is being developed recently. In FIG. 3, the large-screen video wall device 60 including four touch display devices arranged in a 2*2 form is illustrated.
As described above, if the video wall device 60 is configured by connecting the plurality of touch display devices DP1 to DP4, the error of the touch operation caused by signal delay may occur. Particularly, in the video wall device 60, a signal delay deviation may also occur between touch ICs of individual touch display devices, and for this reason, an error may likely occur when performing touch operation in a whole screen of the video wall device 60.
In the large-screen touch display devices, it is thus beneficial to develop a method that can reduce or prevent an error of touch operation caused by a delay deviation of the touch report of each of the plurality of source/touch driving ICs 35. It is also beneficial to develop a method that can reduce or prevent an error of touch operation caused by a signal delay deviation between a plurality of touch ICs.